Kotlin 开发Android 笔记1：Kotlin介绍及项目配置

• Kotlin 是一个基于 JVM 的新的编程语言，由 JetBrains 开发。与Java相比，Kotlin的语法更简洁、更具表达性，而且提供了更多的特性。
• Kotlin是使用Java开发者的思维被创建的，Intellij作为它主要的开发IDE。对于 Android开发者，有两个有趣的特点：
• 对Java开发者来说，Kotlin是非常直觉化的，并且非常容易学习。语言的大部 分内容都是与我们知道的非常相似，所以能迅速地掌 握它。
• AndroidStudio作为目前最流行的Android开发工具，能够非常完美地理解、编译运行Kotlin代码。

—第一步：环境搭建——- 
开始的唠叨：

• 我用的Android版本是2.1.2,Gradle是gradle-2.12版本，目前Kotlin的最新版本是1.0.3。

• 可能是因为我Gradle版本较低的原因 ，在项目中尝试配置了多次Kotlin1.0.3版本都失败了，最终我使用的是kotlin1.0.2版本。 
  配置过程如下： 
  1，给AndroidStudio工具安装Kotlin插件： 
  

  直接安装上图中带红圈的Kotlin插件，重启AndroidStudio即可。网上说是也要安装图中第二个插件（Kotlin Extensinons For Android）， 
  2，在项目中添加配置Kotlin代码： 
  2.1，在Project对应的build.gradle文件中添加如下代码：

<code class="hljs perl has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">// Top-level build file where you can add configuration options common to all <span class="hljs-sub" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">sub</span>-projects/modules.buildscript {</span>    ext.kotlin_version = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'1.0.2'</span> //kotlin版本    repositories {        jcenter()    }    dependencies {        classpath <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'com.android.tools.build:gradle:2.1.2'</span>        classpath <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"org.jetbrains.kotlin:kotlin-gradle-plugin:<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$kotlin_version</span>"</span> //kotlin依赖    }}allprojects {    repositories {        jcenter()    }}task clean(type: Delete) {    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">delete</span> rootProject.buildDir}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>

2.2,在module对应的build.gradle文件 中添加有Kotlin注释的代码：

<code class="hljs rust has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">apply plugin: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'com.android.application'</span>apply plugin: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'kotlin-android'</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//添加这行代码</span>android {    compileSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">24</span>    buildToolsVersion <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"23.0.3"</span>    sourceSets {        main.java.srcDirs += <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'src/main/kotlin'</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 注明Kotlin路径</span>    }    defaultConfig {        applicationId <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.ldm.kotlin"</span>        minSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">16</span>        targetSdkVersion <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">24</span>        versionCode <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>        versionName <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1.0"</span>    }    buildTypes {        release {            minifyEnabled <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>            proguardFiles getDefaultProguardFile(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'proguard-android.txt'</span>), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'proguard-rules.pro'</span>        }    }}dependencies {    compile fileTree(include: [<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'*.jar'</span>], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">dir</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'libs'</span>)    testCompile <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'junit:junit:4.12'</span>    compile <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'com.android.support:appcompat-v7:24.0.0'</span>    compile <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//直接使用build.gradle中的kotlin版本</span>    compile <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'com.android.support:recyclerview-v7:24.0.0'</span>}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li></ul>

rebuild下工程就可以了。

—-第二步：通过kotlin实现RecycleView显示列表数据—— 
1，MainActivity中代码

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">package <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ldm</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.kotlin</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.os</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Bundle</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.support</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.v</span>7<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.app</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.AppCompatActivity</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.support</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.v</span>7<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.widget</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.LinearLayoutManager</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.support</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.v</span>7<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.widget</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.RecyclerView</span>//Kotlin中创建类MainActivity,用“：”表示继承自AppCompatActivityclass MainActivity : AppCompatActivity() {    //定义一个集合变量，并赋值    private val items = listOf(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据1"</span>,            <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据21/8"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据17"</span>,            <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据111"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据1"</span>,            <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据1"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Kotlin DEMO数据17"</span>)    //实现onCreate(）方法，关键字“fun”    override fun onCreate(savedInstanceState: Bundle?) {        super<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.onCreate</span>(savedInstanceState)        setContentView(R<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.layout</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.activity</span>_main)        //  findViewByid()的方式初始化RecyclerView        val recycle_view = findViewById(R<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.id</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.recycle</span>_view) as RecyclerView<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        //实例化LinearLayoutManager对象，LinearLayoutManager(this)创建了一个对象的实例        //对象实例化也是与Java中有些不同。如你所见，我们去掉了  new 关键 字。        recycle_view<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.layoutManager</span> = LinearLayoutManager(this)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        //初始化Adapter并设置数据        recycle_view<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.adapter</span> = FirstKotlinAdapter(items)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    }}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li></ul>

2，RecyclerView对应数据适配器代码 ：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">package <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">com</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ldm</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.kotlin</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.support</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.v</span>7<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.widget</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.RecyclerView</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.view</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ViewGroup</span>import android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.widget</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.TextView</span>//定义数据适配器，通过“：”继承自RecyclerView<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Adapter</span>public class FirstKotlinAdapter(val items: List<String>) : RecyclerView<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Adapter</span><FirstKotlinAdapter<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ViewHolder</span>>() {    //创建ViewHodler    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {        return ViewHolder(TextView(parent<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.context</span>))    }    //绑定ViewHolder并设置数据    override fun onBindViewHolder(holder: ViewHolder, position: Int) {        holder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.textView</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.text</span> = items[position]    }    //实现getItemCount，处理数据的条目数量    override fun getItemCount(): Int = items<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.size</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>    //定义ViewHolder，现在只需要一个  TextView    class ViewHolder(val textView: TextView) : RecyclerView<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ViewHolder</span>(textView)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul>

目前是把适配器代码类和MainActivity类放在一下包下面的，否则会报错，当然可以不放在一个包中，像Java一样可以导包的，后期会写相关笔记。

3，布局文件代码

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><FrameLayout xmlns:android=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://schemas.android.com/apk/res/android"</span>    android:layout_width=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>    android:layout_height=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>>    <android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.support</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.v</span>7<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.widget</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.RecyclerView</span>        android:id=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"@+id/recycle_view"</span>        android:layout_width=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>        android:layout_height=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span> /></FrameLayout></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

第一个Kotlin项目ok啦